1. Technical Field
The present invention relates, in general, to the precision folding of sheet material and, more particularly, relates to preparing the sheet material for bending using punching, stamping, roll-forming, embossing and similar processes, and then bending or folding the sheet into three-dimensional structures.
2. Description of Related Art
The present method and apparatus are based upon slitting and grooving geometries disclosed in depth in the above set forth related applications, which are each incorporated herein by reference in their entireties. In these related applications several techniques or manufacturing processes for forming slits and grooves that will precisely control bending of a wide variety of sheet material are disclosed, including laser cutting, water jet cutting, stamping, punching, molding, casting, stereo lithography, roll forming, machining, chemical-milling, photo-etching and the like. Some of these processes for fabricating bend-inducing slit geometries can be more expensive than others. For example, laser cutting will inherently involve additional cost as compared to, for example, punching or stamping, but punching and stamping may not be particularly well suited to sheet material of relatively heavy gauge.
The precision bending slit geometries of the above-identified related applications may be advantageously applied to numerous structures which are formed from relatively thin gauge sheet material. These structures tend to be more driven by the need for complex and precise bending patterns than they are by strength or fatigue resistance requirements. An example of one type of structure which can be formed of a relatively thin gauged sheet material, and yet requires precision and complex bending, is electronic component chassis, such as, computers, audio receivers, television sets, DVD players, etc.
As is noted in prior related U.S. patent application Ser. No. 10/672,766, flat sheets, which are slit or grooved in accordance with the teachings of that prior related application, can have electrical components mounted to the flat sheets using “pick-and-place” techniques. The sheets may then be folded into enclosures or housings in which all of the components are spatially related in the desired positions inside the housing. The “pick-and-place” techniques greatly reduce cost, as does the ability to fold a flat sheet into a precisely dimensioned enclosure using relatively low-force bending techniques. While such electronic chassis can be formed using laser cutting or water jet cutting, there is considerable advantage if lower cost slit-forming or groove-forming techniques can be employed. Thus, lower cost fabrication processes such as punching, stamping, roll-forming or the like, will be highly advantageous to use with relatively thin gauge material if they do not lose the precision advantages that the slits geometries of the related applications can produce.
Moreover, slit-forming techniques, such as punching, stamping and roll-forming, can produce slits which have essentially zero kerf or slit width dimension, while laser and water jet cutting remove material and product slits having a measurable kerf or width dimension. Sheets having zero kerf slits have the advantage of being more closed along the bend line after the sheets are bent. Thus, they do not tend to open up as much during bending as sheets having measurable kerf dimensions. This makes the zero kerf sheets amenable to coating with a protective layer that will seal and close the bend line to allow them to be used in applications in which electro-magnetic shielding, corrosion resistance, attractive appearance, or fluid tightness is required.
Accordingly, it is an object of the present invention to provide a method for preparing sheet material for precision bending along a bend line, which method is relatively low in cost and adaptable to a wide range of applications employing sheet material.
A further object of the present invention is to provide a low cost method for preparing sheet material for bending, which method is capable of precise bending free of cumulative bending errors, is suitable for complex bending patterns, and requires only minimal force to effect bending.
Another object of the present invention is to provide a sheet of material for bending in which slits or grooves are formed using low-cost manufacturing processes that are capable of producing structures which can be sealed, are fluid-tight, corrosion resistant or must have an attractive appearance.
The bendable sheet material and bend-inducing sheet forming method of the present invention have other objects and features of advantage which will be set forth in more detail hereinafter in the following Best Mode of Carrying Out the Invention, as exemplified and illustrated by the accompanying drawing.